Electromagnetic Coil Apparatuses for Surgical Navigation and Corresponding Methods

ABSTRACT

An electromagnetic device includes a jig and multiple wires. The jig includes a center member and coil-separating blocks. The coil-separating blocks protrude from the center member and are separated from each other to provide a coil channels. Each of the wires is wrapped on the jig, around the center member, and in one of the coil channels to form one of a multiple coils. Each of the coils is configured to connect to an electromagnetic navigation system and generate respective electromagnetic fields to be emitted relative to a subject.

FIELD

The disclosure relates to electromagnetic navigation procedures, andmore particularly to coil arrays for generating or receivingelectromagnetic fields.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Electromagnetic-based navigation procedures include a surgeon using anavigation system to track a position of a surgical instrument in athree dimensional (3-D) space. In addition to the surgical instrument,the navigation system also includes a localizer and a processor. Thelocalizer generates electromagnetic fields (or first signals), which aredetected by the surgical instrument. The surgical instrument generatesand/or outputs second signals in response to the first signals. Theprocessor then determines a position of the surgical instrument based onthe second signals.

The navigation system can assist in determining a location of a trackeddevice on a pointer probe and/or on a surgical instrument, such as ascalpel, a catheter, a suction device, or a deep brain stimulationprobe. A pointer probe may be used to track a position of an instrumentnot having a tracking device. A tracked device may refer to the pointerprobe, the surgical instrument or a device on the pointer probe or thesurgical instrument. The position of the tracked device can bedetermined relative to a subject (e.g., a patient). The position of thetracked device can be illustrated on a display relative to the subjectby superimposing an icon or image of the tracked device on an image ofthe subject.

Image data of the subject is often acquired for display prior to,during, and/or after a procedure on the subject. An image of the subjectand the corresponding image data can be registered to the subject. Theimage data can define a first three-dimensional space (or image space).The subject can define a second three-dimensional space (or physicalspace) to which the image data is registered. Registration can beperformed using multiple processes.

An electromagnetic (EM) navigation system can be used to acquire ordetermine navigation information, including tracked locations of varioustracking devices and relative locations to registered image data. In anEM navigation system, EM fields are generated by a localizer and sensedby one or more tracking devices. The localizer can be positioned near orrelative to the subject space. The tracking devices can be positioned onor in association with a surgical instrument. The EM fields can beaffected by conductive or magnetic materials located in an area of theEM fields. Examples of conductive materials are metals, conductivepolymers, and impregnated polymeric materials. An example of a magneticmaterial is soft ferromagnetic iron.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

An electromagnetic device is provided and includes a jig and multiplewires. The jig includes a center member and coil-separating blocks. Thecoil-separating blocks protrude from the center member and are separatedfrom each other to provide a coil channels. Each of the wires is wrappedon the jig, around the center member, and in one of the coil channels toform one of a multiple coils. Each of the coils is configured to connectto an electromagnetic navigation system and generate respectiveelectromagnetic fields to be emitted relative to a subject.

In other features, another electromagnetic field device is provided andincludes a jig and a wire. The jig includes a pair of end members and acenter member. The center member is disposed between the pair of endmembers. The pair of end members and the center member together providea coil channel. The coil channel includes dividers. The center member,the dividers, and the end member together provide wire channels. Thewire is wrapped on the center member and in the wire channels to providea coil. The coil is configured to connect to an electromagneticnavigation system and generate an electromagnetic field to be emittedrelative to a subject.

In other features, a method is provided and includes forming a first jigto include a center member and coil-separating blocks. Thecoil-separating members protrude from the center member and provide coilchannels. The coil channels are segregated by each other and include afirst channel and a second channel. A first wire is wrapped on the firstjig, around the center member, and in the first channel to form a firstcoil. A second wire is wrapped on the first jig, around the centermember and the first coil, and in the second channel to form a secondcoil. The first wire and the second wire are configured to connect to anelectromagnetic navigation system and generate respectiveelectromagnetic fields to be emitted relative to a subject.

In other features, another method is provided and includes determining anumber of jigs, including a first jig, to be included in a transmit coilarray. The jigs are formed. Each of the jigs is formed to include acenter member and a pair of end members. The center member is disposedbetween the pair of end members. The pair of end members and the centermember together provide a coil channel. Wires are wrapped on the jigs.Each of the wires is wrapped on one of the center members and in one ofthe coil channels of a respective one of the jigs to provide a coil. Thejigs are mounted on a base plate to form the transmit coil array. Eachof the jigs is mounted in a respective location on the base plate. Thecoils are configured to connect to an electromagnetic navigation systemand generate electromagnetic fields to be emitted relative to a subject.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an environmental view of an operating room having anelectromagnetic navigation system in accordance with the presentdisclosure.

FIG. 2 is a perspective view of a transmit coil array including jigseach having a multiple coils in accordance with the present disclosure.

FIG. 3 is a perspective view of a jig with three orthogonally wrappedcoils for the transmit coil array of FIG. 2.

FIG. 4 is a side view of the jig and orthogonally wrapped coils of FIG.3.

FIG. 5 is a perspective view of a jig having divided wrapping channelsin accordance with the present disclosure.

FIG. 6 is a perspective view of a transmit coil array including multiplejigs each having a respective coil in accordance with the presentdisclosure.

FIG. 7 is a perspective view of a jig and a corresponding coil for thetransmit coil array of FIG. 6.

FIG. 8 is a side view of the jig and coil of FIG. 7.

FIG. 9 is a perspective view of a jig with a divided coil channel and acorresponding coil in accordance with the present disclosure.

FIG. 10 is a side view of the jig and coil of FIG. 9.

FIG. 11 is a side view of the jig and coil of FIG. 9 illustrating acrossover section in accordance with the present disclosure.

FIG. 12 is a perspective view illustrating a portion of a transmit coilarray with single coiled jigs mounted in respective orientations and inaccordance with the present disclosure.

FIG. 13 is a transmit coil array manufacturing machine in accordancewith an embodiment of the present disclosure;

FIG. 14 illustrates a method of manufacturing and installing thetransmit coil array of FIG. 2 in accordance with the present disclosure.

FIG. 15 illustrates a method of manufacturing and installing thetransmit coil arrays of FIGS. 6 and 12 in accordance with the presentdisclosure.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

A localizer of an EM navigation system may include a transmit coil array(TCA). Although the localizers referred to and/or disclosed herein areprimarily described as including TCAs (or coil arrays) for transmittingsignals, the TCAs may be used for receiving signals. The TCA can includemultiple sets of EM coils. Each set of the EM coils may include threeorthogonally positioned coils that are used to generate EM fields. Otherarrangements are disclosed below. The coil arrangements include singularcoil arrangements and coil arrangements with coils that are notorthogonal to each other. Orthogonally positioned coils have respectivecenter axes that are at right angles relative to each other. EMnavigation is dependent on a precise and lengthy calibration process forcalibrating the TCA. The calibration process can also cause a“bottleneck” in a manufacturing process of a navigation system.

The calibration process is primarily performed due to inconsistencies,irregularities, and varying differences in TCAs. This includesdifferences in coil placements, number of windings of each coil, lengthsof coil wires, sizes of coils, spacing between coils, etc. The followingdisclosed implementations provide TCAs that can minimize calibrationprocesses of TCAs and/or eliminate the need for calibrating TCAs.Examples of TCAs and corresponding manufacturing methods are shown inFIGS. 2-12 and 14-15. An example EM navigation system 20 is shown inFIG. 1. The EM navigation system 20 may include any of the TCAs shownand/or described with respect to FIGS. 2-12 and 14-15.

Although the EM navigation system 20 is primarily described with respectto performing a procedure on a human patient, the EM navigation system20 may be used to perform a procedure on other animate and/or inanimatesubjects. Also, the implementations disclosed herein may be applied toother EM systems and for purposes other than for position tracking ofdevices. For example, the implementations may be used to generate EMfields in a transcranial magnetic stimulation system. Also, proceduresdisclosed herein can be performed relative to a volume, a mechanicaldevice, and/or an enclosed structure. The volume may be of an animate orinanimate object. The subject can be an object that includes an enclosedmechanical device.

The EM navigation system 20 performs a guided procedure. The guidedprocedure can be, for example, a surgical procedure, a neural procedure,a spinal procedure, and an orthopedic procedure. The EM navigationsystem 20 allows a user, such as a surgeon 21, to view on a display 22 aposition of an instrument 110 in a coordinate system. The coordinatesystem can be related to an image, such as in an image guided procedure,or can be related to an imageless procedure.

The EM navigation system 20 can operate as an image-based system or asan imageless system. While operating as an imageless system, the EMnavigation system 20 can register the subject space to a graphicaldisplay representing an area of the subject 26, rather than to both thesubject space and an image space. Image data of the subject 26 need notbe acquired at any time, although image data can be acquired to confirmvarious locations of instruments or anatomical portions of the subject26. Positions of the subject 26 can be tracked and positions of theinstrument 110 relative to the subject 26 can be tracked.

While operating as an imageless system, a position of an anatomicalstructure can be determined relative to the instrument and the positionsof the anatomical structure and the instrument can be tracked. Forexample, a plane of an acetabulum can be determined by touching severalpoints with the instrument 110. As another example, a position of afemur can be determined in a similar manner. The position of theinstrument 110 and the anatomical structure can be shown on a displaywith icons or graphics. The display, however, may not show actual imagedata captured of the subject 26. Other data can be provided, such asatlas data or morphed atlas data. The atlas data can be image data thatis generated or generalized from the subject 26. For example, a brainatlas can be generated based on detail analysis of image data of a brainof a patient. Operation of the EM navigation system 20 as an image basedsystem is further described below.

The EM navigation system 20 can be used to navigate or track rigid andflexible instruments. Examples of rigid instruments include drillmotors, probes, awls, drill bits, large outer diameter (OD) needles,large or inflexible implants, etc. Examples of flexible instrumentsinclude catheters, probes, guide wires, small OD needles, small orflexible implants, deep brain stimulators, electrical leads, etc. Theinstrument 110 can be used in any region of a body of the subject 26.The EM navigation system 20 and instrument 110 can be used in variousminimally invasive procedures, such as arthroscopic, percutaneous,stereotactic, or in an open procedure.

Although the EM navigation system 20 is described as acquiring imagedata using an imaging device 28, other data may be acquired and/or used,such as patient and non-patient specific data. The imaging device 28acquires pre-, intra-, or post-operative image data and/or real-timeimage data of a subject 26. The imaging device 28 can be, for example, afluoroscopic x-ray imaging device that may be configured as a C-armhaving an x-ray source 30 and an x-ray receiving device 32. Otherimaging devices may be included and mounted on the imaging device 28.Calibration and tracking targets and radiation sensors may be included.The imaging device 28 may be part of a fluoroscopic system, such as abi-plane fluoroscopic system, a ceiling fluoroscopic system, a cath-labfluoroscopic system, a fixed C-arm fluoroscopic system, an isocentricC-arm fluoroscopic system, a three dimensional fluoroscopic system, etc.

The EM navigation system 20 further includes an imaging devicecontroller 34. The imaging device controller 34 controls the imagingdevice 28 to (i) capture x-ray images received at the x-ray receivingsection 32, and (ii) store the x-ray images. The imaging devicecontroller 34 may be separate from the imaging device 28 and/or controlthe rotation of the imaging device 28. For example, the imaging device28 can move in the direction of arrow 28 a or rotate about alongitudinal axis 26 a of the subject 26. This allows anterior orlateral views of the subject 26 to be imaged. Each of these movementsinvolves rotation about a mechanical axis of the imaging device 28 via amember 36.

X-rays can be emitted from the x-ray source 30 and received at the x-rayreceiving section 32. The x-ray receiving section 32 can include acamera that can create the image data from the received x-rays. Othersuitable imaging devices and/or systems may be used to create or captureimage data. For example, a magnetic resonance imaging system or apositron emission tomography system may be used. Further, an imagertracking device 38 may be included to track a position of the x-rayreceiving section 32 of the imaging device 28 at selected times by, forexample, the C-arm controller 34. The image data can then be forwardedfrom the C-arm controller 34 to a processing module of a navigationcomputer 40 wirelessly or via a link 41. The navigation computer 40 caninclude a processing module that is configured to execute instructionsto perform a procedure.

A work station 42 can include the navigation computer 40, the display22, a user interface 44, and an accessible memory system 46. The imagedata may be transmitted from the C-arm controller 34 to the work station42 or to a tracking system 50. The navigation computer 40 may be aportable computer, such as a laptop computer or a tablet computer.

The work station 42 displays the image data as an image on the display22. The user interface 44 may be a keyboard, a mouse, a touch pen, atouch screen, or other suitable interface. The user interface 44 allowsthe user 21 to provide inputs to control the imaging device 28, via theC-arm controller 34, or adjust display settings of the display 22. Thework station 42 can also be used to control and receive data from a coilarray controller (CAC) 54 having a navigation device interface (NDI) 56.

While the imaging device 28 is shown in FIG. 1, any other alternative2D, 3D or 4D imaging modality may also be used. For example, any 2D, 3Dor 4D imaging device, such as isocentric fluoroscopy, bi-planefluoroscopy, ultrasound, computed tomography (CT), multi-slice computedtomography (MSCT), T1 weighted magnetic resonance imaging (MRI), T2weighted MRI, high frequency ultrasound (HIFU), positron emissiontomography (PET), optical coherence tomography (OCT), intra-vascularultrasound (IVUS), ultrasound, intra-operative, computed tomography(CT), single photo emission computed tomography (SPECT), and/or planargamma scintigraphy (PGS) imaging devices may be used. Any of theseimaging devices may be used to acquire 2D, 3D or 4D pre- orpost-operative and/or real-time images or image data of the subject 26.The images may also be obtained and displayed, generally, in two orthree dimensions. In more advanced forms, 3D surface rendering regionsare achieved of the subject, which may be rendered or changed in time(fourth dimension). The 3D surface rendering regions may be achieved byincorporating subject data or other data from an atlas or anatomicalmodel map or from pre-operative image data captured by MRI, CT, orechocardiography modalities.

Image data sets from hybrid modalities, such as positron emissiontomography (PET) combined with CT, or single photon emission computertomography (SPECT) combined with CT, can also provide functional imagedata superimposed onto anatomical data to be used to reach target siteswithin the subject 26. The imaging device 28, as shown in FIG. 1, canprovide a virtual bi-plane image using a single-head C-arm fluoroscopeby rotating the imaging device 28 about at least two planes. The twoplanes could be orthogonal planes and used to generate two-dimensionalimages. The two-dimensional images can be converted to three-dimensionalvolumetric images. By acquiring images in more than one plane, an iconrepresenting the location of the instrument, introduced and advanced inthe subject 26, may be superimposed in more than one view on the display22. This allows simulated bi-plane or multi-plane views, including twoand three-dimensional views. The instrument 110 may include, forexample, an impacter, a stylet, a reamer driver, taps, a drill, deepbrain stimulators, electrical leads, needles, implants, probes, or otherinstrument.

The EM navigation system 20 further includes a tracking system 50. Thetracking system 50 includes a localizer 52, which may also be referredto as a transmit coil array (TCA), a tracking array, or a transmit coilassembly. Examples of localizers and corresponding components are shownin FIGS. 2-12. The TCA 52 includes coil arrays 52 a that can transmit orreceive. The tracking system 50 includes the CAC 54. The localizer 52,an instrument tracking device 100 of an instrument 110, and a dynamicreference frame (DRF) 58 are connected to the CAC 54 via the NDI 56. TheCAC 54 and the NDI 56 can be provided in a CAC/NDI container 60. The NDI56 may have communication ports that communicate with the localizer 52,the instrument tracking device 100 and/or the DRF 58 wirelessly or viawires.

The DRF 58 can include a DRF member 58 a and a removable tracking device58 b. Alternatively, the DRF 58 can include the tracking device 58 bthat is formed integrally with the DRF member 58 a. For example, thetracking device 58 b can be connected directly to the subject 26. Thetracking device 58 b is a coil sensor that performs as an emitter or areceiver to sense one or more EM fields, or other appropriate devicethat can be tracked by the tracking system 50. Also, the tracking device58 b can be wired to other controllers, processors, modules, etc. of theEM navigation system 20.

The localizer 52 may be or include any of the TCAs shown and/ordescribed with respect to FIGS. 2-14. Although a single localizer isshown in FIG. 1, additional localizers may be included to supplement EMfields generated by the localizer 52 and/or to provide additional EMfields. Supplementing EM fields generated by the localizer 52 and/oradding additional EM fields can increase a navigation area in which toperform a procedure and/or to accurately conduct navigation. The coilarrays 52 a can transmit signals that are received by the DRF 58 and atleast one tracking device (e.g., the instrument tracking device 100).

The tracking device 100 can be associated with the instrument 110 at alocation that is generally positioned within the subject 26 during aprocedure. The DRF 58 can then transmit and/or provide signals basedupon the received/sensed signals of the generated fields from thelocalizer 52 and/or other localizers.

The tracking system 50 or components of the tracking system 50 may beincorporated into other systems or devices in the operating theatre. Forexample, one of the localizers can be incorporated into the imagingdevice 28. The transmitter coil arrays 52 a can be attached to the x-rayreceiving section 32 of the imaging device 28. The localizer 52 may bepositioned at any location within the operating theatre. For example,the localizer 52 may be positioned at the x-ray source 30. Also, thelocalizer 52 can be positioned: within or on top of an operating roomtable 120; below the subject 26; on side rails associated with the table120; or on the subject 26 and in proximity to a region being navigatedwithin.

Also, the coil arrays 52 a can include multiple coils (e.g., inductioncoils) that are each operable to generate distinct EM fields into theregion being navigated, such as a region within the subject 26(sometimes referred to as patient space). The coil arrays 52 a arecontrolled or driven by the CAC 54. The CAC 54 can transmit a signal viaa transmission line 112 to the localizer 52. The coil arrays 52 a canhave more than one coil that is driven by the CAC 54. The signal may betime division multiplexed or frequency division multiplexed. In oneimplementation, each of the coil arrays 52 a includes at least threeorthogonal coils that generate three orthogonal EM fields. The coilarrays 52 a can include any number of coils. The localizer 52 caninclude any number of coil arrays. The coils can be oriented in variousdifferent positions and may not be in a position orthogonal to othercoils. In this regard, each coil of the coil arrays 52 a may be drivenseparately, at distinct times, simultaneously, and/or with respectivecurrent signals having predetermined frequencies.

Upon driving the coils in the coil arrays 52 a with the coil arraycontroller (or control module) 54, EM fields are generated within thesubject 26 in the area where the medical procedure is being performed.The EM fields can induce currents in the tracking devices 58 b, 100. Inresponse to the induced currents, the tracking devices 58 b, 100generate signals, which are provided to the NDI 56 and can be forwardedto the CAC 54 and/or the navigation computer 40. The NDI 56 may provideelectrical isolation for the EM navigation system 20. The NDI 56 caninclude amplifiers, filters and buffers to directly interface with thetracking devices 58 b, 100. Alternatively, the tracking devices 58 b,100 may communicate wirelessly or via wires with the NDI 56.

The tracking device 100 can be in a handle or inserter thatinterconnects with an attachment and may assist in placing an implant.The instrument 110 can include a graspable or manipulable element at aproximal end and a sensor that can be fixed near the manipulable elementor at a distal working end. The tracking device 100 can include an EMsensor to sense the EM fields generated by the localizer 52 and induce acurrent in the tracking device 100. As illustrated in FIG. 1, anddiscussed further herein, the tracking device 100 associated with theinstrument 110 can also be placed completely or partially within thesubject 26.

The DRF 58 can be connected to the NDI 56 to forward the information tothe CAC 54 and/or the navigation computer 40. The DRF 58 may include amagnetic and/or EM field detector (e.g., the tracking device 58 b). TheDRF 58 may be fixed to the subject 26 and adjacent to the region wherenavigation is occurring such that any movement of the subject 26 isdetected as relative motion between the localizer 52 and the DRF 58. TheDRF 58 can be interconnected with the subject 26. Any relative motion isindicated to the CAC 54, which updates registration correlation andmaintains accurate navigation. The DRF 58 may include a selected numberof coils. For example, the coils may be mutually orthogonal with eachother and share a center axis around which the coils are wound. Thecoils may be configured in various non-coaxial or co-axial coilconfigurations.

The DRF 58 may be affixed externally to the subject 26 and/or adjacentto a region of navigation (e.g., affixed on a skull of the subject 26,to a bone of the subject 26, or to skin of the subject 26). The DRF 58may be affixed using an adhesive patch and/or a tensioning system. TheDRF 58 may also be removably attachable to a fiducial marker. Fiducialmarkers can be anatomical landmarks and/or artificial members attachedor positioned on the subject 26.

In operation, the EM navigation system 20 creates a map between pointsin image data or an image space and corresponding points in a subjectspace (e.g., points in an anatomy of a patient or in a patient space).After the map is created, the image space and subject space areregistered to each other. This includes correlating position (locationand orientations) in an image space with corresponding positions in asubject space (or real space). Based on the registration, the EMnavigation system 20 may illustrate a position of the instrument 110relative to an image of the subject 26 in a super-imposed image. Forexample, the instrument 110 can be illustrated relative to a proposedtrajectory and/or a determined anatomical target. The work station 42alone and/or in combination with the CAC 54 and/or the C-arm controller(or control module) 34 can: identify the corresponding point on thepre-acquired image or atlas model relative to the tracked instrument110; and display the position on display 22 and relative to an image134. This identification is known as navigation or localization. An iconrepresenting a localized point or an instrument is shown on the display22 within two-dimensional image planes, as well as on three and fourdimensional images and models. The work station 42, the CAC 54, and theC-arm controller 34 and/or selected portions thereof can be incorporatedinto a single system or implemented as a single processor or controlmodule.

To register the subject 26 to the image 134, the user 21 may use pointregistration by selecting and storing particular points from thepre-acquired images and then touching the corresponding points on thesubject 26 with a pointer probe or any appropriate tracked device. TheEM navigation system 20 analyzes the relationship between the two setsof points that are selected and computes a match, which allows for acorrelation of every point in the image data or image space with itscorresponding point on the subject 26 or the subject space.

The points that are selected to perform registration or form a map arethe fiducial markers, such as anatomical or artificial landmarks. Again,the fiducial markers are identifiable on the images and identifiable andaccessible on the subject 26. The fiducial markers can be artificiallandmarks that are positioned on the subject 26 or anatomical landmarksthat can be easily identified in the image data. The artificial fiducialmarkers can also form part of the DRF 58. Any appropriate number of thefiducial markers can be provided with and/or separate from the DRF 58.

The EM navigation system 20 may also perform registration using anatomicsurface information or path information (referred to asauto-registration). The EM navigation system 20 may also perform 2D to3D registration by utilizing the acquired 2D images to register 3Dvolume images by use of contour algorithms, point algorithms or densitycomparison algorithms.

In order to maintain registration accuracy, the EM navigation system 20tracks the position of the subject 26 during registration and navigationwith the DRF 58. This is because the subject 26, DRF 58, and localizer52 may all move during the procedure. Alternatively the subject 26 maybe held immobile once the registration has occurred, such as with a headholder. Therefore, if the EM navigation system 20 does not track theposition of the subject 26 or an area of an anatomy of the subject 26,any subject movement after registration would result in inaccuratenavigation within the corresponding image. The DRF 58 allows thetracking system 50 to track the anatomy and can be used duringregistration. Because the DRF 58 is rigidly fixed to the subject 26, anymovement of the anatomy or the localizer 52 is detected as the relativemotion between the localizer 52 and the DRF 58. This relative motion iscommunicated to the CAC 54 and/or the processor 48, via the NDI 56,which updates the registration correlation to thereby maintain accuratenavigation.

The DRF 58 can be affixed to any portion of the subject 26, and can beused to register the subject 26 to the image data, as discussed above.For example, when a procedure is being performed relative to a skull orcranium 26 s, the DRF 58 can be interconnected with the cranium 26 s.

The tracking system 50 can position the localizer 52 adjacent to thepatient space to generate an EM field (referred to as a navigationfield). Because points in the navigation field or patient space isassociated with a unique field strength and direction, the trackingsystem 50 can determine the position (which can include location andorientation) of the instrument 110 by measuring the field strength anddirection or components of the EM field at the tracking device 100. TheDRF 58 is fixed to the subject 26 to identify the location of thesubject 26 in the navigation field. The tracking system 50 continuouslydetermines the relative position of the DRF 58 and the instrument 110during localization and relates this spatial information to subjectregistration data. This enables image guidance of the instrument 110within and/or relative to the subject 26.

To obtain a maximum accuracy it can be selected to fix the DRF 58 ineach of at least 6 degrees of freedom. Thus, the DRF 58 or any trackingdevice, such as the tracking device 100, can be fixed relative to axialmotion X, translational motion Y, rotational motion Z, yaw, pitch, androll relative to a portion of the subject 26 to which the trackingdevice 58 b is attached. Any appropriate coordinate system can be usedto describe the various degrees of freedom. Fixing the DRF 58 relativeto the subject 26 in this manner can assist in maintaining maximumaccuracy of the EM navigation system 20.

The instrument 110 can be any appropriate instrument (e.g., a catheter,a probe, a guide, etc.) and can be used for various mechanisms andmethods, such as delivering a material to a selected portion of thesubject 26, such as within the cranium 26 s. The material can be anyappropriate material such as a bioactive material, a pharmacologicalmaterial, a contrast agent, or any appropriate material. As discussedfurther herein, the instrument 110 can be precisely positioned(including location and orientation) via the EM navigation system 20 andotherwise used to achieve a protocol for positioning the materialrelative to the subject 26 in any appropriate manner, such as within thecranium 26 s. The instrument 110 may also include a brain probe toperform deep brain stimulation.

As discussed above, an EM field can be generated by the localizer 52.The EM field is generated to define a navigation field. The navigationfield can, however, be distorted by various distorting objects includingthe operating table 120, the imaging device 28, various instruments,etc.

FIG. 2 shows a TCA 150 that includes jigs 152, 154, 156. Each of thejigs 152, 154, 156 has a coil array with respective coils. The jigs 152,154, 156 are held in place relative to each other via end plates 158,160. The jigs 152, 154, 156 are further described with respect to FIGS.3-5. The end plates 158, 160 may include first tabs 162, which areinserted into respective holes in the jigs 152, 154, 156. An adhesivemay be used to attach the first tabs 162 to the jigs 152, 154, 156. Theend plates 158, 160 may also include mounting holes 163 and/or secondtabs 164. The mounting holes 163 and/or second tabs 164 may be used tomount the TCA 150 onto an object in an EM navigation system and/ornavigation theatre. For example, as shown in FIG. 1, the TCA 52 may bereplaced with the TCA 150 and be attached to the table 120 on which thesubject 26 is examined and/or a procedure is performed. The coil jigs152, 154 and 156 can be oriented at various angles relative to the endplates 158, 160. The coil jigs 152, 154 and 156 can be orientedorthogonally to the end plates 158, 160 or at other angles relative tothe end plates 158, 160.

In FIGS. 3-4, a jig 170 and corresponding coils 172, 174, 176 are shown.The jigs 152, 154, 156 of FIG. 2 may be implemented as the jig 170.Although the jig 170 is shown as having three orthogonally positionedcoils, any number of coils may be included and may be positioned invarious orientations on the jig 170 to provide respective EM fields. Anorientation of a coil may refer to a radial wrapping location, an axisof a jig around which the coil is wrapped, coordinates of a center ofthe coil relative to a center of a corresponding jig, a set ofcoordinates of the coil relative to a reference point of a TCA or acomponent (e.g., an end plate or a base plate) of a TCA, an angularposition of the coil relative to a component (e.g., an end plate or abase plate) of a TCA, etc.

In the example shown, the jig 170 includes a center member 178 and eightcoil-separating blocks 180. The term “block” as used herein may refer toan object having a predetermined shape. Although the coil-separatingblocks 180 are shown as having a generally cubular shaped geometry, thecoil-separating blocks 180 may have various shaped geometries. Thecoil-separating blocks 180 protrude away from the center member 178 andform wire wrapping (or coil) channels 182, 184, 186. The coil channels182, 184, 186 may be externally accessible for wrapping of respectivewires to form the coils 172, 174, 176. A single coil channel is providedfor each of the coils 172, 174, 176. Each of the coils 172, 174, 176 iswound around the center member 178 and/or a common center point 190 ofthe jig 170 and in a respective one of the coil channels 182, 184, 186.Each of the coils 172, 174, 176 may have a predetermined number ofwindings. In one implementation, each of the coils 172, 174, 176 has thesame number of windings. In another implementation, the coils 172, 174,176 have different numbers of windings. Coils on a jig may have the sameor a different number of windings than corresponding coils on anotherjig. The diameter of each of the coil channels 182, 184, 186 of the jig170 is different and is predetermined such that each of the coils 172,174, 176 are wrapped on the jig 170 without contacting other ones of thecoils 172, 174, 176.

Sides of the jig 170 may include, for example, tabs and/or holes 192, asshown. The tabs and/or holes 192 may be located in the coil-separatingblocks 180 and accessible from external surfaces of the coil-separatingblocks 180. The coil-separating blocks 180 may each have any number ofexternal surfaces at various angles and/or positions relative to thecenter member 178 and the center point 190. The tabs and/or holes 192may be used to attach the jig 170 to corresponding mounting (or end)plates, as shown in FIG. 2. The tabs and/or holes 192 may also be usedto hold the jig 170 during wrapping of the wires onto the jig 170. Thejig 170 may be held in, for example, a fixture, a gripper, and/or a viceduring the wrapping of the wires.

Ends 194 of the wires on the jig 170 may be received into correspondingconnectors. Example connectors are shown in FIGS. 6-11. The connectorsmay be connected to the CAC 54 via the NDI 56 and/or to a processor,controller, and/or control module of an EM navigation system (e.g., theEM navigation system 20).

FIG. 5 shows a jig 200 having divided wire wrapping channels (or coilchannels) 202, 204, 206. The jig 200 includes a center member 208 andprotruding coil-separating blocks 210. Each of the coil channels 202,204, 206 may have predetermined dimensions including widths and depths.Each of the coil channels 202, 204, 206 is configured to receive arespective coil and is divided by dividers 212 to form multiple wirewrapping channels (or wire channels) 214. The dividers 212 may each havea predetermined width, outer circumference, and/or diameter. The wirechannels 214 may each have predetermined widths, depths, innercircumferences, and inner diameters. The dimensions of the coil channels202, 204, 206, the dividers 212, and the wire channels 214 may bepredetermined based on, for example, predetermined levels of current tobe applied to the corresponding coils, predetermined operatingtemperatures of the coils, and/or predetermined EM field characteristics(e.g., electric and/or magnetic vector field values).

Each of the coil channels 202, 204, 206 has a set of dividers(respective ones of the dividers 212) and a set of wire channels(respective ones of the wire channels 214). Each of the sets of dividersmay have a respective diameter. Each of the sets of wire channels mayhave a respective inner diameter and outer diameter, where the outerdiameter matches the diameter of the corresponding dividers.

The dividers 212 extend radially outward from the center member 208 andare segregated by the coil channels 202, 204, 206 such that the dividers212 are non-contiguous annularly and/or toroidally-shaped discs. Thedividers 212 and wire channels 214 can provide stacked layers ofalternating coil windings and dividers. The elements of the jig 200including the protruding coil-separating blocks 210, the center member208 and the dividers 212 may be separate elements or may be implementedas a unitary structure, as shown. Although the jig 200 is shown as beinggenerally cube-shaped, the jig 200 may have a different shape.

Each of the wire channels 214 is configured to receive a wire of a coil.A wire may be wrapped one or more times around the center member 208 andin each of the wire channels 214. In this implementation, the dividers212 separate each winding of a coil or sets of windings of a coil forprecise wrapping of the wire of the coil on the jig 200. Each set mayhave the same number of windings or may have a respective number ofwindings. This provides accurate, predictive, consistent placement ofeach winding of the coil.

The jigs of FIGS. 2-6 allow for iterative manufacturing of a TCA suchthat multiple TCAs satisfying the same requirements and having the samedimensions can be produced with predictable and consistentcharacteristics. These characteristics can include jig dimensions, wirelengths, number of windings per coil, number of windings betweenadjacent dividers of a jig, coil and winding placements, and coildimensions (width, inner and outer diameters, and thickness).

FIG. 6 shows another TCA 220 that includes multiple jigs 222. The TCA220 may replace the TCA 52 of FIG. 1 and be attached to the table 120 onwhich the subject 26 is examined and/or a procedure is performed. Eachof the jigs 222 is a single-coiled jig with a respective coil. The jigs222 are mounted in respective locations on a base plate 224. The baseplate 224 may have tabs (or holes) 226 and/or recessed sections 228 foraccurate placement of jigs on the base plate 224. The tabs (or holes)226 align with holes (or tabs) 230 in the jigs 222. The recessedsections 228 may have holes 232 through which wires 234 on the jigs mayextend, as shown. Ends 236 of the wires 234 on each of the jigs may bereceived into corresponding connectors 238, which may be on oppositesides of the base plate 224 than the jigs. The connectors 238 may beconnected to the CAC 54 via the NDI 56 and/or to a processor,controller, and/or control module of the EM navigation system 20 ofFIG. 1. Although in FIG. 6 three jigs and/or twelve recessed sectionsare shown, the TCA 220 may have any number of jigs and correspondingrecessed sections.

Although the three jigs 222 shown have the same orientation on the baseplate 224, the jigs of the TCA 220 may have different orientations. Anexample of jigs having different orientations is shown in FIG. 12. Thecoils of the jigs that have the same orientation can be used to providea single EM field. EM field energy generated by the coils having thesame orientation add together to increase the size of the EM field.Coils of jigs having different orientations can be used to providemultiple EM fields having different electric and magnetic field vectorsextending in respective directions. This allows for increased fielddiversity.

Although the jigs of FIG. 6 are shown as having a single coil with asingle coil orientation, each of the jigs may have any number of coilswith different orientations. A first example of a jig that may be usedin the TCA 220 of FIG. 6 is shown in FIGS. 7-8. A second example of ajig that may be used in the TCA 220 of FIG. 6 is shown in FIGS. 9-11.

FIGS. 7-8 show a jig 240 and a corresponding coil 242. The jig 240 isshown as being cylindrical in shape with a coil channel 244 locatedbetween two end members 246. A wire is wrapped around a center member248 and inner circumference of the coil channel 244. The jig 240 mayhave holes (or tabs) 250 for mounting on a base plate (e.g., the baseplate 224 of FIG. 6) and/or for use in holding the jig 240 duringwrapping of a wire on the jig 240 to form the coil 242. The jig 240 mayalso have a center opening 252 for mounting the jig 240 on a wrappingfixture, bracket, coupling, or rod. As an example, the center opening252 may be cross-shaped (or irregular prism shaped), as shown, toreceive a jig mounting portion of a fixture. The jig mounting portionmay be rotated to facilitate in wrapping the wire on the jig 240 to formthe coil 242. Ends 254 of the wire may be received by a connector 256.

FIGS. 9-11 show a jig 260 with a coil channel 262 and a correspondingcoil 264. The coil channel 262 is between end members 266. The coilchannel 262 includes dividers 268 and wire channels 270. The dividers268 extend radially outward from a center member 272. The end members266, the center member 272 and the dividers 268 may be separate elementsor may be implemented as a unitary structure, as shown. One of the endmembers 266 may include a hole or a notch 274, as shown in FIG. 9. Ends276 of a wire wrapped on the jig 260 may extend through the notch 274and be received by a connector 278. This allows for the wire to bepassed through a hole in, for example, a base plate.

The jig 260 may have a crossover section 280 between the end members 266and separating each of the dividers 268, such that the dividers 268 arenon-contiguous annularly and/or toroidally-shaped discs. The wire, whenwrapped on the jig 260, may be wrapped around the center member 272,around a center axis 282, in the wire channels 270 and in a firstdirection parallel (indicated by arrow 284) to the center axis 282. Thewire may then be wrapped in a second direction (indicated by arrow 286)opposite the first direction. To facilitate wrapping in the firstdirection and second direction the wire may switch between wire channelsin the crossover section 280. First portions 288 of the wire extendthrough the crossover section 280 while wrapping the wire in the firstdirection. Second portions 290 of the wire extend through the crossoversection 280 while wrapping the wire in the second direction. The secondportions 290 may crossover the first portions 288 in the crossoversection 280. Portions of the EM field generated by the portions 288, 290of the coil in the crossover section 280 may cancel each other.

The crossover section 280 may be wedge-shaped with a narrow end 292extending through one of the end members 266. This allows ends 276 ofthe wire to (i) extend through the end member and, for example, a baseplate, and (ii) be received by the connector 278. The crossover section280 allows for accurate positioning of crossover locations. Crossoverlocations refer to locations in the crossover section 280 in which thewire transitions between two of the wire channels 270.

Although not shown, one or more of the wires of the coils on the jigs ofFIGS. 3-5 may be wrapped in multiple directions and perform crossoverssimilar to the wire of FIG. 11. For example a first wire may crossoverbetween wire channels in spaces (or gaps) provided by a second coilchannel.

FIG. 12 shows a portion 300 of a TCA with single coiled jigs 302, 304mounted in respective orientations. The jigs 302, 304 and correspondingcoils 306, 308 are shown mounted on a base plate 310 in differentorientations. The jigs 302, 304 are angled upward from the base plate310 via orienting blocks 312, 314. For example only, the orientingblocks 312, 314 may be triangular prism shaped and mounted on the baseplate 310. The orienting blocks 312, 314 may be located in recessedsections 316 of the base plate 310 and may have first holes (or tabs)318, which are attached to second tabs (or holes) on the base plate 310.The orienting blocks 312, 314 may have third tabs (or holes) 320, whichconnect to fourth holes (or tabs) on the jigs 302, 304. The orientingblocks 312, 314 may be adhered via an adhesive to the base plate 310and/or the jigs 302, 304. Although plates, jigs and orienting blocks aredescribed herein as being connected via tabs and corresponding holes,the plates, jigs, and orienting blocks may be connected to each othervia other suitable techniques.

The orienting blocks 312, 314 have jig mounting surfaces 322.Directional placement of the orienting blocks 312, 314 and angles of thejig mounting surfaces 322 relative to the base plate 310 may bepredetermined to set the orientation of the jigs 302, 304 andcorresponding coils 306, 308. End members 324 of the jigs 302, 304 maybe at the same angles relative to the base plate 310 as thecorresponding jig mounting surfaces 322. This allows coils to not bewrapped around the same center member of the same jig and be placed invarious positions and/or orientations relative to each other. As anexample, the coils 306, 308 may be orthogonally positioned relative toeach other and/or be used to generate orthogonal EM fields. Any numberof jigs and coils may be included in the TCA. The jigs 302, 304 andcoils 306, 308 may have the same or different orientations. In oneimplementation, more than two jigs and coils have the same orientationand more than two jigs and coils have different orientations.

In one implementation, twelve jigs and corresponding coils are included.The twelve jigs and twelve coils include three sets. Each of the setsincludes four jigs and four coils. The jigs and coils of a single setare orientated in the same direction (e.g., have center axes that are inparallel with each other). A center axis being an axis around which acoil is wrapped. The jigs and coils of different sets are orienteddifferently (e.g., have center axes that are not in parallel with eachother).

Each of the jigs and corresponding coils of FIGS. 2-12 may be referredto collectively as an EM device. Although the jigs and/or EM devices ofFIGS. 2-12 are shown as having a single coil and wire for each coilchannel, the jigs and/or EM devices may have more than one coil and/orwire in each coil channel. Also, although the coils and correspondingcoil channels and center members of FIGS. 2-12 are circular shaped, thecoils and corresponding coil channels and center members may be shapeddifferently. For example, the coils and corresponding coil channels andcenter members may be square shaped, rectangular shaped, ellipticalshaped, and/or polygonally shaped.

The jigs, end plates, and base plates of FIGS. 2-12 and/or other jigs,end plates, and/or base plated disclosed herein may be formed of, forexample, thermally stable plastic and/or ceramic. This allows thesecomponents to: withstand expansions and/or contractions of coils due totemperature changes of the coils; maintain structural integrity duringchanges in temperatures of the coils and the components; and to maintainrespective dimensions within predetermined ranges during changes in thetemperatures. The jigs, end plates, and base plates disclosed herein maybe formed of, for example, nylon, polyvinylchloride, polycarbonate,polyester, polysulphone, polyphenylenesulphone, polyetheretherketone,polyphenylene, sulphide, polyetherimide, polyamide-imide, and/orpolybenzimidazole. The materials of the jigs, end plates, and baseplates may have coefficients of thermal expansion that are less thanpredetermined values. The jigs, end plates, and base plates disclosedherein may be constructed using injection molding, machining, and/orrapid prototyping. As an example, the jigs, end plates, and base platesdisclosed herein may be formed using, for example, stereolithography. Asanother example, alumina ceramic may be printed using astereolithography process or a cast process to form one or more of thejigs, end plates, and base plates disclosed herein.

FIG. 13 shows a TCA manufacturing machine 350 that includes amanufacturing system 352. The TCA manufacturing machine 350 andmanufacturing system 352 are provided as an example, the plates, jigs,TCAs, and orienting blocks disclosed herein may be formed and/orassembled using other suitable techniques. The TCA manufacturing machine350 and the manufacturing system 352 may include a control module 354, aproduction printer 356, a supply area 358, and a production system 360.Each of the control module 354, the production printer 356, the supplyarea 358, and the production system 360 may be included in the TCAmanufacturing machine 350 and/or the manufacturing system 352 or may beseparate from the TCA manufacturing machine 350 and the manufacturingsystem 352.

The control module 354 may control operations in the production printer356, supply area 358 and/or production system 360 and/or may be incommunication with modules in the production printer 356, supply area358 and/or production system 360. The production printer 356, supplyarea 358 and/or production system 360 may have respective controlmodules or may share a single control module, as shown.

The production printer 356 may be, for example, a stereolithographyprinter or other type of production printer or production machine. Theproduction printer 356 may include, for example, a resin bath 362 inwhich plates, jigs and/or orienting blocks may be formed via a laser 364and scanner system 366. The plates, jigs and/or orienting blocks may bestored in the supply area 358.

The supply area may store plates 370, jigs 372, orienting blocks 374 andwires 376 and include motors, grippers, and/or other machinery to movethe plates 370, jigs 372, orienting blocks 374 and/or wires 376 from theproduction printer 356 to the supply area 358 or from the supply area358 to the production system 360. The wires 376 may be pre-cut topredetermined lengths or may be cut as used in the production system360.

The production system 360 may include a wire wrapping station 380 and aTCA assembly station 382 and corresponding grippers and/or motors tomove, wire wrap and connect the jigs 372 to the plates 370. The jigs 372may be wrapped in the wire wrapping station 380 and mounted between endplates, on a base plate and/or in housing in the TCA assembly station382. The production system 360 may include wire cutters for cuttingwires to predetermined lengths.

FIG. 14 shows a method of manufacturing and installing the TCA of FIG.2. Although the following tasks are primarily described with respect tothe implementations of FIGS. 2-5, the tasks may be easily modified toapply to other implementations of the present disclosure. The tasks maybe iteratively performed as part of an automated process. Any of thetasks may be performed manually and/or by a TCA manufacturing machine(e.g., the TCA manufacturing machine 350 of FIG. 13) and/or assemblyline controlled by one or more control modules (referred to below as“the control module”). The method may begin at 400.

At 402, coil characteristics are determined. The coil characteristicsmay include, for example, lengths of wires, number of windings per coil,number of windings per wire channel, etc.

At 404, a number of jigs to be included in a TCA and correspondingdimensions of the jigs are determined. This may be based on the coilcharacteristics, a number of jigs per EM field to be generated, a numberof EM fields to be generated, a maximum current level or current rangesof corresponding coils, and characteristics of EM fields to begenerated.

At 406, the jigs (e.g., the jigs of FIGS. 2-5) are formed having thepredetermined dimensions to provide mounting locations for coils havingpredetermined shapes and orientations relative to each other and thejigs.

At 408, a first wire is wrapped on one of the jigs (referred to in thebelow tasks 410, 412 as “the jig”), in a first coil channel, and arounda center member and a center point of the jig to form a first coil. Thefirst wire is wrapped according to corresponding and predetermined coilcharacteristics.

At 410, a second wire is wrapped on the jig, in a second coil channel,and around (i) the center member, (ii) the center point, and (iii) thefirst coil. The second wire may be wrapped, such that the second coil isat a predetermined position relative to the first coil. The second wireis wrapped according to corresponding and predetermined coilcharacteristics.

At 412, a third wire is wrapped on the jig, in a third coil channel, andaround (i) the center member, (ii) the center point, (iii) the firstcoil, and (iv) the second coil. The third wire may be wrapped, such thatthe third coil is at a predetermined position relative to the first coiland the second coil. The third wire is wrapped according tocorresponding and predetermined coil characteristics.

Although the above tasks include three wire wrapping tasks, any numberof wire wrapping tasks may be included.

At 414, the control module determines whether there is another jig to bewrapped. If there is another jig to be wrapped, task 408 is performed,otherwise task 416 is performed.

At 415, the end plates are formed. At 416, the one or more jigs may beinstalled between end plates (e.g., the end plates) and/or mountedwithin a housing to form the TCA. The jigs may be press-fitted,adhesively attached and/or connected to the end plates.

At 418, the TCA may be installed in an EM navigation system (e.g., theEM navigation system 20). At 420, the TCA may be calibrated via thenavigation computer 40 or other controller, processor and/or controlmodule of the EM navigation system. In one implementation, task 420 isnot performed. The TCA is then used in a procedure with having beencalibrated. The EM navigation system may perform the procedure based onpredetermined characteristics of the TCA, components of the TCA (coils,jigs, plates, etc.), and EM field characteristics (e.g., electric andmagnetic field vector values). The characteristics of the TCA mayinclude any of the TCA characteristics disclosed herein includingdimensions and characteristics of the components in the TCA. The methodmay end at 422.

FIG. 15 shows a method of manufacturing and installing the TCAs of FIGS.6 and 12. Although the following tasks are primarily described withrespect to the implementations of FIGS. 6-12, the tasks may be easilymodified to apply to other implementations of the present disclosure.The tasks may be iteratively performed as part of an automated process.The tasks may be performed by a TCA manufacturing machine (e.g., the TCAmanufacturing machine 350 of FIG. 13) and/or assembly line controlled byone or more control modules. The method may begin at 450.

At 452, coil characteristics are determined. The coil characteristicsmay include, for example, lengths of wires, number of windings per coil,number of windings per wire channel, etc.

At 454, a number of jigs to be included in a TCA and correspondingdimensions of the jigs are determined. This may be based on the coilcharacteristics, a number of jigs per EM field to be generated, a numberof EM fields to be generated, a maximum current level or current rangesof corresponding coils, and characteristics of EM fields to begenerated.

At 456, the jigs (e.g., the jigs of FIGS. 2-5) are formed having thepredetermined dimensions to provide mounting locations for coils havingpredetermined shapes and orientations relative to each other and thejigs.

At 458, wrapping respective wires on each of the jigs formed at 454. Thewires may be wrapped in respective coil channels and/or wire channels ofthe jigs. Each of the wires is wrapped according to corresponding andpredetermined coil characteristics.

At 460, a base plate and/or orienting blocks are formed. The orientingblocks may be formed at 460 as part of the base plate or may be formedat 454 as part of the jigs. The orienting blocks are formed with jigmounting surfaces at predetermined angles.

At 462, the orienting blocks may be mounted on the base plate atpredetermined positions. At 464, the jigs may be mounted on theorienting blocks and/or mounted within a housing to form the TCA. Thejigs are mounted on the orienting blocks in predetermined positions andto place the jigs and wires in predetermined orientations relative tothe base plate.

At 466, the TCA may be installed in an EM navigation system (e.g., theEM navigation system 20). At 468, the TCA may be calibrated via thenavigation computer 40 or other controller, processor and/or controlmodule of the EM navigation system. In one implementation task 468 isnot performed. The EM navigation system may perform the procedure basedon predetermined characteristics of the TCA, components of the TCA(coils, jigs, plates, orienting blocks, etc.), and EM fieldcharacteristics (e.g., electric and magnetic field vector values). Thecharacteristics of the TCA may include any of the TCA characteristicsdisclosed herein including dimensions and characteristics of thecomponents in the TCA. The method may end at 470.

The above-described tasks of FIGS. 14 and 15 are meant to beillustrative examples; the tasks may be performed sequentially,synchronously, simultaneously, continuously, during overlapping timeperiods or in a different order depending upon the application. Also,any of the tasks may not be performed or skipped depending on theimplementation and/or sequence of events.

The above-described implementations, allow for coils to be wound on jigsin a consistent and repeatable manner. This allows for a reduction incalibration time of TCAs and/or elimination of a calibration process dueto the predictable physical and operating characteristics of the TCAs.

The wireless communications described in the present disclosure can beconducted in full or partial compliance with IEEE standard 802.11-2012,IEEE standard 802.16-2009, IEEE standard 802.20-2008, and/or BluetoothCore Specification v4.0. In various implementations, Bluetooth CoreSpecification v4.0 may be modified by one or more of Bluetooth CoreSpecification Addendums 2, 3, or 4. In various implementations, IEEE802.11-2012 may be supplemented by draft IEEE standard 802.11ac, draftIEEE standard 802.11ad, and/or draft IEEE standard 802.11ah.

It should be understood that one or more steps within a method may beexecuted in different order (or concurrently) without altering theprinciples of the present disclosure.

In this application, including the definitions below, the term modulemay be replaced with the term circuit. The term module may refer to, bepart of, or include an Application Specific Integrated Circuit (ASIC); adigital, analog, or mixed analog/digital discrete circuit; a digital,analog, or mixed analog/digital integrated circuit; a combinationallogic circuit; a field programmable gate array (FPGA); a processor(shared, dedicated, or group) that executes code; memory (shared,dedicated, or group) that stores code executed by a processor; othersuitable hardware components that provide the described functionality;or a combination of some or all of the above, such as in asystem-on-chip.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes,and/or objects. The term shared processor encompasses a single processorthat executes some or all code from multiple modules. The term groupprocessor encompasses a processor that, in combination with additionalprocessors, executes some or all code from one or more modules. The termshared memory encompasses a single memory that stores some or all codefrom multiple modules. The term group memory encompasses a memory that,in combination with additional memories, stores some or all code fromone or more modules. The term memory may be a subset of the termcomputer-readable medium. The term computer-readable medium does notencompass transitory electrical and electromagnetic signals propagatingthrough a medium, and may therefore be considered tangible andnon-transitory. Non-limiting examples of a non-transitory tangiblecomputer readable medium include nonvolatile memory, volatile memory,magnetic storage, and optical storage.

The apparatuses and methods described in this application may bepartially or fully implemented by one or more computer programs executedby one or more processors. The computer programs includeprocessor-executable instructions that are stored on at least onenon-transitory tangible computer readable medium. The computer programsmay also include and/or rely on stored data.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

Terms such as “first,” “second,” and other numerical terms when usedherein do not imply a sequence or order unless clearly indicated by thecontext. Thus, a first element, component, region, layer or sectiondiscussed herein could be termed a second element, component, region,layer or section without departing from the teachings of the exampleembodiments.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. An electromagnetic device comprising: a jigcomprising a center member, and a plurality of coil-separating blocksprotruding from the center member and are separated from each other toprovide a plurality of coil channels; and a plurality of wires, whereineach of the plurality of wires is wrapped on the jig, around the centermember, and in one of the plurality of coil channels to form one of aplurality of coils, wherein each of the plurality of coils is configuredto connect to an electromagnetic navigation system and generaterespective electromagnetic fields to be emitted relative to a subject.2. The electromagnetic device of claim 1, wherein: the plurality of coilchannels are orthogonal to each other; and the coils are orthogonal toeach other.
 3. The electromagnetic device of claim 1, wherein the centermember and the plurality of coil-separating blocks are implemented as aunitary structure.
 4. The electromagnetic device of claim 1, wherein:the plurality of coil channels comprise dividers and wire channels; andeach of the plurality of wires are wrapped in one of the wire channels,around the center member, and between two of the dividers or between oneof the dividers and one of the coil-separating blocks.
 5. Theelectromagnetic device of claim 4, wherein: the dividers separate setsof windings of one of the plurality of wires; and each of the sets ofwindings comprises two or more windings.
 6. The electromagnetic deviceof claim 4, wherein: the plurality of coil channels are segregated withgaps between segregated portions of the plurality of coil channels,wherein a first coil channel is segregated by a second coil channel suchthat gaps of the first coil channel are in the second coil channel; andeach of the plurality of wires switch between wire channels in the gapsof the segregated portions of the plurality of coil channels.
 7. Theelectromagnetic field device of claim 1, wherein the jig includes atleast one of a plastic material and a ceramic material.
 8. Theelectromagnetic field device of claim 1, wherein the jig comprises atleast one crossover section in which at least one of the wires isswitched between two wire channels.
 9. A transmit coil array comprising:a plurality of the electromagnetic device of claim 1; and a plurality ofend plates, wherein the plurality of electromagnetic devices areconnected to and between the end plates.
 10. The transmit coil array ofclaim 9, wherein: the end plates comprise tabs; and the tabs areinserted into respective holes in the jig.
 11. A system comprising: thetransmit coil array of claim 9; a controller configured to generatefirst signals via the plurality of coils of the transmit coil arraywithout previous calibration of the transmit coil array; and a trackingdevice configured to (i) receive the first signals, and (ii) generatesecond signals based on the first signals, wherein the controller isconfigured to track a position of the tracking device based on thesecond signals and during a procedure on the subject.
 12. Anelectromagnetic field device comprising: a jig comprising a pair of endmembers, and a center member disposed between the pair of end members,wherein the pair of end members and the center member together provide acoil channel, wherein the coil channel comprises dividers, and whereinthe center member, the dividers, and the end member together providewire channels; and a wire wrapped on the center member and in the wirechannels to provide a coil, wherein the coil is configured to connect toan electromagnetic navigation system and generate an electromagneticfield to be emitted relative to a subject.
 13. The electromagnetic fielddevice of claim 12, wherein the jig comprises a crossover section inwhich the wire is switched between two of the wire channels.
 14. Theelectromagnetic field device of claim 13, wherein the wire crossesitself a plurality of times in the crossover section.
 15. Theelectromagnetic field device of claim 12, wherein the jig includes atleast one of a plastic material and a ceramic material.
 16. A transmitcoil array comprising: a plurality of the electromagnetic device ofclaim 12; and a base plate, wherein the plurality of electromagneticdevices are mounted on the base plate and in respective orientations.17. The transmit coil array of claim 16, further comprising orientingblocks mounted on the base plate and between the jigs of theelectromagnetic devices and the base plate, wherein: orienting blockscomprise jig mounting surfaces on which the jigs of the electromagneticdevices are mounted; and the jigs and the wires are oriented relative toeach other and relative to the base plate based on angles of jigmounting surfaces relative to the base plate.
 18. The transmit coilarray of claim 16, wherein: the base plate comprise first tabs; thefirst tabs are inserted into respective holes in the orienting blocks;the orienting blocks comprise second tabs; and the second tabs areinserted into respective holes in the jigs.
 19. The transmit coil arrayof claim 16, wherein: the jigs comprise notches; the base platecomprises holes; and the wires extend through the notches of the jigsand the holes in the base plate.
 20. A system comprising: the transmitcoil array of claim 16; a controller configured to generate firstsignals via coils of the transmit coil array without previouscalibration of the transmit coil array; and a tracking device configuredto (i) receive the first signals, and (ii) generate second signals basedon the first signals, wherein the controller is configured to track aposition of the tracking device based on the second signals and during aprocedure on the subject.
 21. A method comprising: forming a first jigto include a center member and a plurality of coil-separating blocks,wherein the coil-separating members protrude from the center member andprovide a plurality of coil channels, and wherein the plurality of coilchannels are segregated by each other and comprise a first channel and asecond channel; wrapping a first wire on the first jig, around thecenter member, and in the first channel to form a first coil; andwrapping a second wire on the first jig, around the center member andthe first coil, and in the second channel to form a second coil, whereinthe first wire and the second wire are configured to connect to anelectromagnetic navigation system and generate respectiveelectromagnetic fields to be emitted relative to a subject.
 22. Themethod of claim 21, further comprising: determining a number of jigs,including the first jig, to be included in a transmit coil array;forming the jigs; attaching the jigs to end plates to form the transmitcoil array; and installing the transmit coil array in theelectromagnetic navigation system.
 23. The method of claim 21, whereinforming the first jig comprises forming the first channel orthogonal tothe second channel.
 24. The method of claim of claim 23, wherein formingthe first jig comprises forming the plurality of coil channels toinclude a third channel, wherein the third channel is formed orthogonalto the first channel and the second channel.
 25. A method comprising:determining a number of jigs, including a first jig, to be included in atransmit coil array; forming the jigs, wherein each of the jigs isformed to include a center member and a pair of end members, wherein thecenter member is disposed between the pair of end members, wherein thepair of end members and the center member together provide a coilchannel; wrapping a plurality of wires on the jigs, wherein each of theplurality of wires is wrapped on one of the center members and in one ofthe coil channels of a respective one of the jigs to provide a coil; andmounting the jigs on a base plate to form the transmit coil array,wherein each of the jigs is mounted in a respective location on the baseplate, wherein the coils are configured to connect to an electromagneticnavigation system and generate electromagnetic fields to be emittedrelative to a subject.
 26. The method of claim 25, further comprisingforming the coil channels of the jigs to include dividers, wherein: thecenter member, the dividers, and the pair of end members of each of thejigs together provide wire channels; and each of the plurality of wiresis wrapped on a respective one of the center members and in the wirechannels of a respective one of the jigs.
 27. The method of claim 25,further comprising mounting the jigs in respective orientations on thebase plate.